In a production procedure of electronic devices, such as IC devices, an electronic device testing apparatus is used for testing performance and functions of the produced electronic devices.
An electronic device testing apparatus as an example of the related art is provided with a test section for conducting a test on IC devices, a loader section for sending pre-test IC devices to the test section and an unloader section for taking out post-test IC devices from the test section and classifying them. The loader section is provided with a buffer stage capable of moving back and forth between the loader section and the test section, and a loader section conveyor device provided with a suction portion for picking up by suction and holding IC devices and capable of moving in a range from a customer tray to a heat plate and from the heat plate to the buffer stage. Also, the test section is provided with a contact arm capable of picking up and holding IC devices by suction and pressing them against sockets of a test head and a test section conveyor device capable of moving in a range of the test section.
In the loader section conveyor device, IC devices carried on the customer tray are picked up and held by the suction portion and loaded on the heat plate and, then, the IC devices heated to be a predetermined temperature on the heat plate are again picked up and held by the suction portion and loaded on the buffer stage. Then, the buffer stage loaded with the IC devices moves from the loader section to the test section side. Next, the test section conveyor device uses the contact arm to pick up and hold the IC devices on the buffer stage and press them against sockets of the test head, so that external terminals (device terminals) of the IC devices are brought to contact with connection terminals (socket terminals) of the sockets.
In that state, by applying to the IC devices test signals supplied to the test head from the tester body through a cable and sending response signals read from the IC devices to the tester body through the test head and cable, electric characteristics of the IC devices are measured.
However, in the series of operations of the test section conveyor device explained above, even when the operation of pressing the IC devices against the sockets fails or the operation of picking up by suction the IC devices on the sockets fails, the next operation is successively performed while IC devices are left on the sockets. If next IC devices are pressed against the sockets for conducting a test, the next IC devices cannot be pressed against the sockets because the previous IC devices remain and the test cannot be conducted normally.
Such a disadvantage as “double placing of IC devices” results in erroneous recognition of a test result of the previous IC device as that of the next IC device and erroneous classification of IC devices, in addition to a disadvantage that the test on IC devices cannot be conducted normally. Also, the sockets and IC devices may be damaged as a result that the IC devices are piled when being pressed.
In the related art, as a countermeasure of such disadvantages, an alarm is set off to draw operator's attention in the case of occurring an erroneous suction, etc. of an IC device and the operator removes the IC device. However, the disadvantages of “double placing of IC devices” cannot be eliminated completely by checking with human eyes.
Note that there is the case of performing a maintenance operation of the electronic device testing apparatus with IC devices placed on the sockets, and again, the same disadvantages arise when removal of the IC devices used in the maintenance operation is forgotten after the operation.